Respiratory polygraphy in sleep apnoea diagnosis. Report of the Swiss respiratory polygraphy registry and systematic review of the literature.

BACKGROUND

Sleep related breathing disorders (SBD) are common and associated with morbidity and mortality. Since polysomnography, the conventional diagnostic gold standard is costly and not generally available, ambulatory respiratory polygraphic sleep studies (RP) are used. To evaluate whether RP reimbursement by health insurance companies was justified, the Swiss Federal Office of Public Health (FOPH) requested registration of RP during 36 months and a literature review on RP. The results are reported here.

METHODS

RP reimbursed from July 2002 to December 2005 by Swiss health insurance companies were analysed. A review of the literature from 2003 comparing RP with PSG was updated. The outcome of interest was the apnoea/hypopnoea index.

RESULTS

Datasets on 11,485 RP were evaluated, 8179 were performed to evaluate suspected obstructive sleep apnoea syndrome (OSAS). In patients with snoring, witnessed apnoea and hypersomnia (n = 4180), 80.2% of RP confirmed OSAS, 3.5% of RP were inconclusive prompting polysomnography. Six studies published between 2003 and 2005 were pooled with a former review of 12 studies. With a mean pre-test probability of 64% for OSAS, the post-test probability after a negative result ranged from 8% (negative likelihood ratio of 0.05) to 23% (negative likelihood ratio of 0.20). The post-test probability after a positive result was within a range of 98% (positive likelihood ratio of 23.8) to 90% (positive likelihood ratio of 5.7).

CONCLUSIONS

In selected patients with clinically suspected OSAS RP allows accurate and simple diagnosis of OSAS. According to the practice in Switzerland as reflected by the registry additional PSG are rarely required, suggesting relevant cost savings by RP. Granting reimbursement for RP as introduced in the meantime by the FOPH seems justified.